Single crystal wafers (e.g., silicon single crystal wafers) are used as a substrate upon which electronic devices (e.g., integrated circuits) are built. Single crystal wafers may be produced by slicing the wafers from a single crystal ingot and subjecting the sliced wafers to various finishing operations such as various lapping, grinding, etching, and polishing steps to produce the finished wafers. Such ingots may be grown by the Czochralski method in which polycrystalline silicon is first melted within a quartz crucible. After the polycrystalline silicon has melted and the temperature equilibrated, a seed crystal is dipped into the melt and subsequently extracted to form a single crystal silicon ingot while the quartz crucible is rotated.
Device manufacturers increasingly require wafers that do not contain gas pockets at the surface of the wafer upon which devices are built. Such gas pockets in the wafer result from gas bubbles in the silicon melt being incorporated into the growing ingot during pulling of the silicon ingot. One source of such bubbles is gas pockets (i.e., bubbles) within the quartz crucible. Molten silicon slowly etches the quartz crucible which allows the gas therein to exit the crucible and enter the silicon melt. Some gases (e.g., oxygen) can dissolve into the melt before incorporation into the ingot. However, some less soluble gases (e.g., argon which is typically used as an insulating gas in the crystal pull chamber) dissolve at a slower rate and the gas bubble becomes incorporated into the silicon ingot thereby forming a gas pocket in the ingot.
A continuing need exits for silicon ingots and wafers with reduced gas pockets as well as crucibles that result in less gas bubbles being incorporated into the silicon ingot during ingot growth. A continuing need also exists for methods for producing crucibles that allow ingots and wafers with less gas bubbles to be produced.
This section is intended to introduce the reader to various aspects of art that may be related to various aspects of the disclosure, which are described and/or claimed below. This discussion is believed to be helpful in providing the reader with background information to facilitate a better understanding of the various aspects of the present disclosure. Accordingly, it should be understood that these statements are to be read in this light, and not as admissions of prior art.